Please ensure BE 2010 r3 is fully patched with sp2 and other updates using live update and tape drivers are using latest Symantec drivers. to install drivers for symante (http://www.symantec.com/docs/TECH17931 ) And also ensure you have disable the following HP services

if they are present in windows services and once done please do a good powet cycle by powering off the tape library and Media server and then powering on the tape drive first and wait for it to be intialized and then power on Media server and check

Hope that helps

Thanks

Sameer

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Download HP Library and Tape Tools, stop the BE services, and run a compression and Read/Write test. You need an empty/unused tape to do so. This will confirm if you have an issue with the tapes or not.

Also, in BE itself, click on a tape that was ejected and check for the following:

1. Compression level. 1:1 or less means you won't backup your full backup set on 1 tape for instance;

2. Hard Write Errors...this indicates a problem with the tape or the drive.